Greenfly, Blackfly and Aphid control
Blackfly, greenfly and all aphids love the garden, and will be prolific in your garden given the chance. They are unslightly, leave a mess and will stunt, if not kill off, your plants if left unchecked. They will go for many different plants, but are especially noticeable on broad beans, nastursiums and roses, where they are sucking up the sap of the plants.
Biological control is always the first line of defence. Try and plant flowers in the garden that will attract bees, ladybirds and loverfly. These insects will go some way to keeping the population of aphids down. However, they are often not seen in the garden early enough. It is possible to purchase parasitic wasps for use in enclosed spaces such as greenhouses, which do a good control job.
Companion planting will help to keep the numbers down, but again will not stop all aphids. The smell of onions and garlic planted near vunerable plants will deter pests. Likewise mint, coriander, dill and oregano are known repellents. Planting tagetes and marigolds near tomatoes and roses works too and is especially successful in the greenhouse.
Nip the tips out of broad beans to slow blackfly progress. Planting nastursiums will attract blackfly and if you are happy to sacrifice the nastursium, then often the blackfly will stay on them, leaving other plants alone.
The only other natural deterent is squashing the bugs between your fingers - a messy and time consuming task.
Chemical solutions are available. Bug clear can be sprayed when infestations occur. Beware that some chemicals are also harmful to bees, so make sure to read the packet.
Vigilance and early action is the key to maintaining a healty garden. Enjoy!